Holley Tuning HELP

I agree that somewhere between 14-18 degrees for your combo, and that should be around 800 rpm with the vacuum hose plugged. It will take several iterations to get the timing and idle fuel mix to a point it makes the most power at idle and just off idle. A little harder to zero in with the 4 speed because you can't just put it in D with your foot on the brake and see if the rpms and vac drop or not. (dropping is because the engine isn't making enough power to overcome the added load. The less it drops the better)

If you're willing to pre-invest some time, use the method at the bottom of my previous post. That is, take the carb off to look at the transfer slot exposure. Then take notes as to how far out the idle speed screw is when the slot is about .020 and .040 showing. (A wire type spark plug gapping gage is a handy reference). Put it back on and try to adjust the timing and fuel mix with the transfer slot square. If you can't, then open the thottle a little more. from your notes you'll know when its getting out of acceptable range. This should save you a bunch of experimentation.

In this case, it is likely ported vacuum will be the best source for the distributor's vacuum. Experiment with both if you want.